1. Field
One embodiment of the present invention relates to a frame interpolation device and more particularly to a frame interpolation device, a frame interpolation method and an image display device which deal with a pull-down signal.
2. Description of the Related Art
Recently, a flat-panel display device such as a large-scale liquid crystal display device has been developed and is popularly used instead of the conventional cathode-ray tube display device. In such a liquid crystal display device, a video signal is displayed according to a standard of 60 Hz (50 Hz in the case of PAL, SECAM) in the case of NTSC, for example. On the other hand, since a cinema signal is formed of 24 frames per second and cannot be displayed on a television receiver as it is, it is necessary to subject the cinema signal to a pull-down process.
In Patent Document 1 (Jpn. Pat. Appln. KOKAI Publication No. 2004-159294), a method is provided to convert a cinema signal of 24 Hz into a moving picture of 48 Hz by forming one interpolation frame for every two frames of the cinema signal of 24 Hz, successively display two original frames for every four frames of the signal of 48 Hz to convert four frames into five frames so as to convert 48 Hz into 60 Hz.
However, the conventional technique disclosed in Patent Document 1 cannot solve the following problem. That is, for example, in the liquid crystal display device which is the display device supplied with a video signal of 60 Hz, there occurs a problem that an afterimage or deformation occurs in a video image which quickly moves, but the above conventional technique cannot cope with this problem. In the conventional technique, a video signal processing method for displaying a signal of 120 Hz by interpolating four frames is described, but since the circuit scale becomes extremely large in order to form a plurality of interpolation frames based on two original frames and it is difficult to attain the above operation. Therefore, there occurs a problem that the problem of how to attain a video signal of, for example, 120 Hz and display a smooth video image by subjecting a video signal of 60 Hz to the interpolation process in the display device cannot be coped with. Further, in the above conventional technique, there occurs a problem that the technique for more smoothly displaying a video signal by performing different processes depending on whether or not the video signal of 60 Hz is a pull-down signal is not disclosed.